Recycling of waste materials is ever increasing in popularity and mirrors the concerns that many people have for the environment. In some cities and regions, recycling is even mandatory. Very often, many people try to conserve natural resources and reuse components of products can help in that effort. One example of mandated recycling is illustrated by the many states that have enacted legislation requiring a deposit on the purchaser of beverage containers in the form of aluminum cans and plastic bottles. The production of aluminum from bauxite is a very energy intensive process and recycling of aluminum cans therefore a cost effective endeavor. Recycling of soda bottles made of polyethylene terephthalate (PET) is another area where recycling has been successfully applied.
Reusing the PET from beverage bottles to form carpet fibers is one area where recycling has achieved certain benefits. Besides reducing the cost of the raw materials, such recycling has also reduced the amount of materials being disposed within landfills. It is not uncommon for carpet manufacturers to use recycled two liter soda bottles in the production of polyester based carpeting. PET polyester carpet is manufactured with yarn created from reclaimed polyester resins.
Post consumer carpet recycling has not become very wide spread. Post consumer carpet refers to the carpet that had been installed in a house or office, but is in need of removal and replacement with new carpeting or other types of flooring. Until recently, once the carpet in a house or office had worn out and was removed, the only destination for disposal had been a landfill. Because of the type of ingredients used in carpet, i.e. thermoplastic polymeric materials, carpet materials are not very biodegradable, and once buried in a landfill, a carpet may take as much as 20,000 years to fully degrade. At the present time, nearly six billion pounds of carpet are discarded per year in the United States, and as landfill space becomes scarcer while petroleum based products become more expensive due to increased crude oil costs, the need to recycle post consumer carpet becomes more necessary and more cost effective.
Carpets like many other composite materials are difficult to recycle effectively because they comprise a number of components made from different materials that have been combined into a finished product. These individual components, once extracted from the post consumer carpet, have significantly more value than as the composite. Carpets are comprised of a backing which supports and hold together a plurality of fibers that extend from the backing, and which farm the pile or surface that is walked on by the user. An adhesive based material may be used to secure the fibers to the backing, and is typically used to secure a secondary backing to the primary backing. Usually one type of polymeric material is used to make the fibers of the carpet pile, a different type of polymeric material is used to make the backing, while the adhesive used is frequently a third type of material. In many carpets, this face fiber that makes up the pile may be nylon, a polyolefin, a polyester, etc. The backing is usually a polypropylene material, although other materials may also be used. Because of the multiplicity of materials, carpet has been difficult to recycle into reusable constituent components because the materials that comprise the carpet can not be readily or easily separated into those individual polymers. While there are some uses for composite polymeric materials, the value of the recycled post consumer carpet increases significantly if the components are separated.
Because of the difficulties in separating the carpet components, some companies have resorted to reusing the carpet as a fuel, and burn the carpet as a source of heat instead of dumping it in a landfill. In the burning method of recycling, the carpet may be burned as a fuel and the heat is used to generate steam which can then be used to generate electricity. The heat generated by the burning carpet can also be used for other purposes. While this reduces landfill dumping, it is not an ideal means of recycling the carpet.
Another approach towards carpet recycling can include melting the carpet rather than burning it, and thereafter attempting to separate the components in the blend based upon their melting or vaporization points. But this process is energy intensive and requires complex equipment. This equipment necessary must prevent each of the distinctive material fibers from burning when, yet must allow them to be heated to the proper melting temperatures to facilitate separation of the components. Additionally, separating those melted composite of carpet materials is not easily performed. Because of the difficulty in separating the melted components of a carpet, this recycled material is usually not used for new carpet, but is instead used in such products like park benches, and other similar items where a blend of different polymers is not objectionable.